csymv(3)

NAME

CSYMV - perform the matrix-vector operation y := al

pha*A*x + beta*y,

SYNOPSIS

SUBROUTINE  CSYMV(  UPLO, N, ALPHA, A, LDA, X, INCX, BETA,
Y, INCY )
    CHARACTER     UPLO
    INTEGER       INCX, INCY, LDA, N
    COMPLEX       ALPHA, BETA
    COMPLEX       A( LDA, * ), X( * ), Y( * )

PURPOSE

CSYMV performs the matrix-vector operation y := alpha*A*x

+ beta*y, where alpha and beta are scalars, x and y are n element

vectors and A is an n by n symmetric matrix.

ARGUMENTS

UPLO - CHARACTER*1

On entry, UPLO specifies whether the upper or lower

triangular part of the array A is to be referenced as follows:

UPLO = 'U' or 'u' Only the upper triangular part

of A is to be referenced.

UPLO = 'L' or 'l' Only the lower triangular part

of A is to be referenced.

Unchanged on exit.

N - INTEGER

On entry, N specifies the order of the matrix A. N

must be at least zero. Unchanged on exit.

ALPHA - COMPLEX

On entry, ALPHA specifies the scalar alpha. Un

changed on exit.

A - COMPLEX array, dimension ( LDA, N )

Before entry, with UPLO = 'U' or 'u', the leading

n by n upper triangular part of the array A must contain the up

per triangular part of the symmetric matrix and the strictly low

er triangular part of A is not referenced. Before entry, with

UPLO = 'L' or 'l', the leading n by n lower triangular part of

the array A must contain the lower triangular part of the symmet

ric matrix and the strictly upper triangular part of A is not

referenced. Unchanged on exit.

LDA - INTEGER

On entry, LDA specifies the first dimension of A as

declared in the calling (sub) program. LDA must be at least max(

1, N ). Unchanged on exit.

X - COMPLEX array, dimension at least

( 1 + ( N - 1 )*abs( INCX ) ). Before entry, the

incremented array X must contain the N- element vector x. Un

changed on exit.

INCX - INTEGER

On entry, INCX specifies the increment for the ele

ments of X. INCX must not be zero. Unchanged on exit.

BETA - COMPLEX

On entry, BETA specifies the scalar beta. When BETA

is supplied as zero then Y need not be set on input. Unchanged

on exit.

Y - COMPLEX array, dimension at least

( 1 + ( N - 1 )*abs( INCY ) ). Before entry, the

incremented array Y must contain the n element vector y. On exit,

Y is overwritten by the updated vector y.

INCY - INTEGER

On entry, INCY specifies the increment for the ele

ments of Y. INCY must not be zero. Unchanged on exit.

LAPACK version 3.0 15 June 2000

CSYMV(3)